The ultrasonic flow rate measuring device is a device that measures a propagation time of an ultrasonic wave which is caused to propagate across a measurement passage while flowing a fluid through the measurement passage, and detects a flow rate of the fluid based on the measured information.
A pair of ultrasonic transmitter-receivers are provided respectively to the opposing short sides of the measurement passage, whose cross-section is rectangular.
These paired ultrasonic transmitter-receivers face each other and transmit/receive a ultrasonic wave between them along a line, which intersects with the flow direction of the measurement passage at a predetermined angle.
Also, an ultrasonic flow rate measuring device has been proposed in which the measurement passage is constructed of multi-layered passages formed by partitioning the measurement passage with a plurality of parallelly arranged partitioning plates in order to improve the measuring accuracy (see Patent Literature 1, for example).
Patent Literature 1: WO2004/074783